Don't show the 'preview' banner on published gallery (#16727)

dev/bots/travis_script.sh

@@ -10,25 +10,43 @@ if [ "$SHARD" = "build_and_deploy_gallery" ]; then
   if [ "$TRAVIS_OS_NAME" = "linux" ]; then
     echo "Building Flutter Gallery for Android..."
     export ANDROID_HOME=`pwd`/android-sdk
-    (cd examples/flutter_gallery; flutter build apk --release)
+    (
+      cd examples/flutter_gallery
+      flutter build apk --release -t lib/main_publish.dart
+    )
     echo "Android Flutter Gallery built"
     if [[ "$TRAVIS_PULL_REQUEST" == "false" && "$TRAVIS_BRANCH" == "dev" && $version != *"pre"* ]]; then
       echo "Deploying to Play Store..."
-      (cd examples/flutter_gallery/android; bundle install && bundle exec fastlane deploy_play_store)
+      (
+        cd examples/flutter_gallery/android
+        bundle install
+        bundle exec fastlane deploy_play_store
+      )
     else
       echo "Flutter Gallery is only deployed to the Play Store on merged and tagged dev branch commits"
     fi
   elif [ "$TRAVIS_OS_NAME" = "osx" ]; then
     echo "Building Flutter Gallery for iOS..."
-    (cd examples/flutter_gallery; flutter build ios --release --no-codesign)
+    (
+      cd examples/flutter_gallery
+      flutter build ios --release --no-codesign -t lib/main_publish.dart
+    )
     echo "iOS Flutter Gallery built"
     if [[ "$TRAVIS_PULL_REQUEST" == "false" ]]; then
       if [[ "$TRAVIS_BRANCH" == "dev" && $version != *"pre"* ]]; then
         echo "Archiving with distribution profile and deploying to TestFlight..."
-        (cd examples/flutter_gallery/ios; bundle install && bundle exec fastlane build_and_deploy_testflight upload:true)
+        (
+          cd examples/flutter_gallery/ios
+          bundle install
+          bundle exec fastlane build_and_deploy_testflight upload:true
+        )
       else
         echo "Archiving with distribution profile..."
-        (cd examples/flutter_gallery/ios; bundle install && bundle exec fastlane build_and_deploy_testflight)
+        (
+          cd examples/flutter_gallery/ios
+          bundle install
+          bundle exec fastlane build_and_deploy_testflight
+        )
         echo "Archive is only deployed to TestFlight on tagged dev branch commits"
       fi
     else

examples/flutter_gallery/lib/gallery/home.dart

@@ -85,6 +85,10 @@ class GalleryHome extends StatefulWidget {
        assert(onTimeDilationChanged != null),
        super(key: key);
 
+  // In checked mode our MaterialApp will show the default "debug" banner.
+  // Otherwise show the "preview" banner.
+  static bool showPreviewBanner = true;
+
   final GalleryTheme galleryTheme;
   final ValueChanged<GalleryTheme> onThemeChanged;
 
@@ -206,15 +210,12 @@ class GalleryHomeState extends State<GalleryHome> with SingleTickerProviderState
       )
     );
 
-    // In checked mode our MaterialApp will show the default "debug" banner.
-    // Otherwise show the "preview" banner.
-    bool showPreviewBanner = true;
     assert(() {
-      showPreviewBanner = false;
+      GalleryHome.showPreviewBanner = false;
       return true;
     }());
 
-    if (showPreviewBanner) {
+    if (GalleryHome.showPreviewBanner) {
       home = new Stack(
         fit: StackFit.expand,
         children: <Widget>[

examples/flutter_gallery/lib/main_publish.dart

@@ -0,0 +1,13 @@
+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'gallery/home.dart';
+import 'main.dart' as other_main;
+
+// This main chain-calls main.dart's main. This file is used for publishing
+// the gallery and removes the 'PREVIEW' banner.
+void main() {
+  GalleryHome.showPreviewBanner = false;
+  other_main.main();
+}